Need a little experiment carried out....

[irving2008]

The stepper motor is definitely applying a torque opposing the lathe and if I just hold the motor it feels like that torque is a function of the phase current - presumably they're proportional. The torque ripple is high though since we're operating it as a single phase motor.

Hmmmm hadn't though about that. Should be powering both windings in parallel then?

I think measuring the torque using the method I suggested earlier would be easier?

Maybe, but a dropping weight and pulley is easy to calibrate